Experts generally recommend seven to nine hours a night for healthy adults. Sleep scientists say new guidelines are needed to take into account an abundance of recent research in the field and to reflect that Americans are on average sleeping less than they did in the past.

Several sleep studies have found that seven hours is the optimal amount of sleep—not eight, as was long believed—when it comes to certain cognitive and health markers, although many doctors question that conclusion.

Other recent research has shown that skimping on a full night's sleep, even by 20 minutes, impairs performance and memory the next day. And getting too much sleep—not just too little of it—is associated with health problems including diabetes, obesity and cardiovascular disease and with higher rates of death, studies show.

"I'm a child of a smoker — my father was a heavy smoker," Koval says. "Really typical to the way the story goes, I started smoking when I was 15."

Now she is president and CEO of Legacy, a foundation devoted to preventing tobacco use.

Koval is working in a rapidly changing landscape. Earlier this month, Reynolds American announced plans to buy its rival Lorillard for $27.4 billion. This move alters the U.S. tobacco market and comes as the number of smokers in the U.S. continues to decline.

In the 1960s, more than 40 percent of Americans smoked. Now, that's down to 18 percent. Not only are fewer people smoking, heavy smokers are consuming fewer cigarettes.

"We are winning the war," Koval says. "I guess from my perspective, we'd rather win the war faster."

She says the overall numbers mask a huge cultural variation.

"I live in Washington, D.C.; we have a low smoking rate here. But if you go to a place like West Virginia, which has the highest smoking rate in the country, the behavior feels completely normalized," Koval says.

Many of us get confused by claims of how much the risk of a heart attack, for example, might be reduced by taking medicine for it. And doctors can get confused, too.

Just ask Karen Sepucha. She runs the Health Decisions Sciences Center at Boston's Massachusetts General Hospital. A few years ago she surveyed primary care physicians, and asked how confident they were in their ability to talk about numbers and probabilities with patients.

"What we found surprised us a little bit," Sepucha says. "Only about 20 percent of the physicians said they were very comfortable using numbers and explaining probabilities to patients."

Doctors, including Leigh Simmons, typically prefer words. Simmons is an internist and part of a group practice that provides primary care at Mass General. "As doctors we tend to often use words like, 'very small risk,' 'very unlikely,' 'very rare,' 'very likely,' 'high risk,' " she says.

But those words can be unclear to a patient.

"People may hear 'small risk,' and what they hear is very different from what I've got in my mind," she says. "Or what's a very small risk to me, it's a very big deal to you if it's happened to a family member."

“EATING foods that contain saturated fats raises the level of cholesterol in your blood,” according to the American Heart Association (AHA). “High levels of blood cholesterol increase your risk of heart disease and stroke.” So goes the warning from the AHA, the supposed authority on the subject. Governments and doctors wag their fingers to this tune the world over. Gobble too much bacon and butter and you may well die young. But what if that were wrong?

Nina Teicholz, an American journalist, makes just that argument in her compelling new book, “The Big Fat Surprise”. The debate is not confined to nutritionists. Warnings about fat have changed how food companies do business, what people eat, and how and how long they live. Heart disease is the top cause of death not just in America, but around the world. The question is whether saturated fat is truly to blame. Ms Teicholz’s book is a gripping read for anyone who has ever tried to eat healthily.

The case against fat would seem simple. Fat contains more calories, per gram, than do carbohydrates. Eating saturated fat raises cholesterol levels, which in turn is thought to bring on cardiovascular problems. Ms Teicholz dissects this argument slowly. Her book, which includes well over 100 pages of notes and citations, covers decades of nutrition research, including careful explorations of academics’ methodology. This is not an obvious page-turner. But it is.

Employers want their workers to be healthy—both for insurance-cost and humane reasons—but aspects of those very jobs can make workers sick. A study published this month in the American Journal of Preventive Medicine found that workers who toiled for more than 40 hours per week or were exposed to a hostile work environment were significantly more likely to be obese.

Both of those are fairly intuitive—long hours at the office can make it hard to squeeze in exercise, and dealing with, shall we say, “a strong personality” all day can make it tempting to indulge in an extra helping of curly fries. (A more tragic explanation would be that people who are already obese are more likely to be harassed at work.)

But surprisingly, the researchers also found that certain industries and occupations in and of themselves correlate with higher obesity rates, even when controlling for the demographic makeup of those jobs.

The study authors used data from the 2010 National Health Interview Survey and connected it to self-reported weight and height information, as well as industry and occupation codes from the Census. For the hostility factor, they asked workers: “During the past 12 months were you threatened, bullied, or harassed by anyone while you were on the job?” (The obesity rate was 13 percent higher among those who said yes.)

Benjamin Reiss on The Slumbering Masses : Sleep, Medicine, and Modern American Life and 24/7 : Late Capitalism and the Ends of Sleep and Dangerously Sleepy : Overworked Americans and the Cult of Manly Wakefulness

Everything you thought couldn’t have a history now has one. Foucault had something to do with this, with his histories of madness and sexuality; and de Certeau — the other Michel — gave verve to the historical activities of wandering around, cooking, and various other non-epic feats. Since the age of the Michels, we’ve had histories of conversation, boredom, shit, death, breasts, penises, tasting, happiness, smiling, laughing, celibacy, masturbation, taking out the trash, obsession, collective joy, and sadness. (The editor of this publication has offered his own entries on crying and slacking.) Things that we do or experience in private, things we might expect to read about in novels or talk about in therapy, have now generated a hidden-histories boomlet. The best of these works not only make the familiar strange, but they make us think differently about history and its intimate relation to our own lives. Read More...

A report released by the American Cancer Society reveals an increase in childhood cancer cases coupled with falling death rates among children and adolescents. Cancer in children, while still much rarer than cancer in adults, remains the second-leading cause of childhood death after accidents.

As the report signals, one aspect of the disease is that it develops differently in children than in adults; there are no preventable causes in childhood cancer and it is more difficult to detect. The study did not offer definitive reasons why the rate continues to rise. The question remains the source of considerable debate in the medical community.

"New diagnoses have inched up each year, most recently to about 187 per 1 million children from infancy to age 19. The increases have been driven by blood and lymphatic system cancers, including acute lymphocytic leukemia and non-Hodgkin’s lymphoma.

Experts are not sure why, but they say better diagnosis could be a factor." Read More...

Sometime in the not-too-distant future, Marie and Antonio Freeman step into a doctor’s office to design their next child.

“Your extracted eggs, Marie, have been fertilized with Antonio’s sperm,” the doctor says. “After screening we’re left with, as you see, two healthy boys and two very healthy girls.”

A monitor displays what looks like soap bubbles that bumped into each other on a green background.

“Naturally, no critical predispositions to any of the major heritable diseases,” the doctor says. “All that remains is to select the most compatible candidate. We might as well start with gender—have you given it any thought?”

“We would want Vincent to have a brother, you know, to play with,” Marie says, referring to her first child. Read More...